The 34-year-old Kingston was granted an uncontested divorce from Fiennes, also 34, in England Tuesday.
The couple met while studying at the Royal Academy of Dramatic Arts and married in 1993, but have not lived together for the past two years.
That's because Fiennes has taken up with the woman who played his mother in Hamlet, Francesca Annis. In addition to her stage work, Annis, who's 19 years older than Fiennes, is well known in Britain for playing the title role in the 1970s TV series Lillie Langtry. The actress has never made much mark in Hollywood, although she did appear as Lady Jessica in the 1984 sci-fi epic Dune.
Kingston, who has relocated to Hollywood, joined the cast of the top-rated NBC drama this fall as the blunt British surgeon Corday, whose professional and personal presence brings an up beat to the tension-plagued medical squad. The actress, formerly a member of the Royal Shakespeare Company, grabbed Hollywood's attention when she starred as lusty adventuress Moll Flanders in an appropriately racy PBS adaptation. (Not to be confused with the dud movie version starring Robin Wright.)
Fiennes, who won a Tony when he took his Hamlet to Broadway and was Oscar-nominated for Schindler's List and The English Patient, will soon be seen in Oscar and Lucinda, an Australian period romance directed by Gillian Armstrong.